BACKGROUND: Rhabdomyoma is the most common cardiac tumor in fetal life. It has frequent association with tuberous sclerosis complex and may lead to heart failure, a potentially fatal condition. The use of transplacental sirolimus, a mammalian target of rapamycin inhibitor, has emerged as a novel treatment in symptomatic fetal rhabdomyomas
however, there are only few cases described. CASE PRESENTATION: A 37-year-old woman at 29 weeks and 4 days of gestation had been diagnosed with fetal cardiac tumor, adhered adjacent to the left ventricle, associated with heart dysfunction and polyhydramnios. Therapy with oral sirolimus was started, and, once serum levels were achieved, cardiac tumor reduction was observed, with progressive resolution of cardiac dysfunction. However, maternal hypertriglyceridemia was developed as a side effect, a rarely discussed theme on previous articles, and was successfully controlled with dose reduction. The patient delivered a male infant at 38 weeks and 2 days of pregnancy with no need of any resuscitation maneuver. CONCLUSION: Transplacental treatment with sirolimus is a promising therapeutic option to treat symptomatic fetal rhabdomyomas, but more data are demanded to determine its efficacy and safety during pregnancy. A close maternal follow-up concerning triglyceride levels is mandatory.